On Easter Sunday, April 23, 1983, nitric acid spilled from a tank car near downtown Denver, Colorado. The spill was neutralized with sodium carbonate.
2 HNO3(aq) + Na2CO3(s) 2 NaNO3(aq) + H2O(l) + CO2(g)
(a) Calculate H° for this reaction.
kJ
Approximately 1.0 104 gal nitric acid was spilled. Assume that the acid was an aqueous solution containing 75.0% HNO3 by mass with a density of 1.42 g/cm3. How much sodium carbonate was required for complete neutralization of the spill? (Hf° for NaNO3(aq) = -467 kJ/mol.)
g
How much heat was evolved?
kJ
(b) According to The Denver Post for April 4,1983, authorities feared that dangerous air pollution might occur during the neutralization. Considering the magnitude of H°, what was their major concern?
To calculate the answers to these questions, we need to follow a step-by-step process:
(a) Calculate H° for this reaction.
To calculate the enthalpy change (H°) for the reaction, we need to subtract the sum of the enthalpies of the reactants from the sum of the enthalpies of the products. The enthalpies of formation (Hf°) are typically used for this calculation.
Enthalpy Change (H°) = Σ Hf°(products) - Σ Hf°(reactants)
Using the given balanced equation:
2 HNO3(aq) + Na2CO3(s) → 2 NaNO3(aq) + H2O(l) + CO2(g)
We can determine the enthalpy change using the enthalpies of formation for each compound:
H° = [2 * Hf°(NaNO3)] - [2 * Hf°(HNO3)] - [1 * Hf°(Na2CO3)] + [1 * Hf°(H2O)] + [1 * Hf°(CO2)]
Substitute the values of the enthalpies of formation from available data and solve for H°.
(b) Authorities feared that dangerous air pollution might occur during the neutralization. Considering the magnitude of H°, what was their major concern?
The magnitude of H° indicates the amount of heat evolved or absorbed during a reaction. In this case, the negative enthalpy change indicates that the reaction is exothermic, meaning it releases heat. The major concern for authorities would be the potential release of large amounts of CO2 gas, as indicated by the reaction equation. The release of a significant quantity of CO2 into the air can lead to pollution and potential health hazards.
I can help you with (a) but the rest I can't.
the answer is -68.5
To get this answer you need to subtract the H° of the reactants from the H° of the products.
[(2*-467)+(-286)+(-393.5)]-[(2*-207)+(-1131)=-68.5